.miz files are zips of two text files. The syntax isn't bad, It looks like a bunch of lua or luaish datastructures. So yeah, with some careful work or ED cooperation a standalone/iPad mission editor would be possible. However, the amount of time/effort needed to re-implement the reasonably complex mission editor interface for a niche segment of the community (people wanting a portable editor) for a niche game on a niche platform means it will almost certainly never happen. Plus, at best it would only duplicate the functionality of the existent editor
